Create a Single-Sprite Variant

Overview

Add a variant to an existing single-sprite asset-generation version (asset_kind = "sprite", one sprite on the whole canvas). Creating a Single-Sprite Variant is the full procedure.

A variant varies the brief the model draws toward: a tighter palette, a stricter operation budget, an added stylistic rule. The asset_kind and the [canvas] are version-level, and an asset-generation case declares no references, so resolution rejects a reference on the case or on any variant.

Steps

1. Choose a consistent slug (flat) and display name (Flat Shading) naming the drawing constraint the variant imposes.
2. Write specs/<slug>.md as an additive brief, stated as a delta against the common brief (“same subject and palette, except …”) with precise, testable constraints. It may reference the common specs. It may not reference another variant’s spec.
3. Create variants/<slug>.toml, a standalone TOML file whose top-level keys are the variant’s fields, and add its path to the variants list in test-case.toml. The first entry in that list is the default variant.

variants/flat.toml

slug = "flat"
name = "Flat Shading"
description = "Same brief, drawn with flat fills only."
spec = [{ source = "specs/flat.md" }]

A spec entry’s dest defaults to its source with any trailing .hbs removed. Spec entries are additive on the common specs, and within one variant two seeded entries may not share a dest. An asset-generation case is judged on one overall rating, so a variant declares no [[review_item]].

Validate

tcab seed   --test-case <slug> --version <version> --variant <new-variant>
tcab prompt --test-case <slug> --version <version> --variant <new-variant>

Seed and render the new variant, then repeat for the existing variants to confirm nothing else changed and the brief still resolves self-contained.